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Vitamin D and Immune Health
What is vitamin D? Vitamin D is a fat-soluble vitamin that plays a key role in many bodily processes, especially those related to bone strength and immune function. Unlike most vitamins, your body can actually make its own vitamin D — but only when your skin is exposed to direct sunlight. Specifically, ultraviolet B (UVB) rays trigger a reaction in the skin that produces a precursor to vitamin D, which is then converted by the liver and kidneys into its active form. Beyond sunlight, vitamin D is found in a limited number of foods. Fatty fish like salmon, sardines, and mackerel are among the richest natural sources. Smaller amounts occur in egg yolks and beef liver, and many everyday products — such as milk, orange juice, and breakfast cereals — are fortified with added vitamin D. Because few foods naturally contain much vitamin D, and because modern lifestyles often limit sun exposure (due to indoor living, sunscreen use, and geographic location), vitamin D deficiency is surprisingly common, even in generally healthy individuals. For this reason, many people turn to supplements to maintain healthy levels year-round. There are two main forms of supplemental vitamin D: D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D2 is typically derived from plant sources like mushrooms exposed to UV light, while D3 usually comes from animal-based sources such as lanolin (from sheep’s wool) or fish oil. There is one vegan source of vitamin D3: lichen, which is an organism comprised of algae or cyanobacteria combined with fungi. Both D2 and D3 can raise vitamin D levels in the blood, but D3 is generally more effective and better absorbed by the body. Absorption also depends on dietary fat, since vitamin D is fat-soluble — meaning it’s best taken with a meal that includes some healthy fat to help your body use it efficiently. However, vitamin D can be made to be water soluble, which greatly increases its bioavailability. How does vitamin D affect the immune system? Vitamin D plays a central role in helping the immune system function efficiently and stay balanced. Rather than simply “boosting” immune activity, it acts more like a modulator — supporting the body’s ability to defend against harmful invaders while also preventing the immune system from becoming overactive. This balancing act is crucial for staying healthy, as both underactive and overactive immune responses can lead to problems. Immune cells throughout the body — including in the skin, lungs, and gut — have receptors for vitamin D, meaning they can respond directly to its presence. In the innate immune system — the body’s first line of defense — vitamin D enhances the ability to recognize and respond to threats quickly. It helps activate important immune cells which are responsible for detecting pathogens and signaling other immune responses. Vitamin D also promotes the production of antimicrobial molecules which act like natural antibiotics and can directly destroy bacteria, viruses, and fungi. These rapid-response mechanisms are essential for containing infections early, before they spread. In the adaptive immune system — which provides more targeted, long-term protection — vitamin D helps fine-tune how immune cells behave. It influences T cells which help keep the immune system in check and prevent excessive inflammation. It also affects B cells, which are responsible for producing antibodies, by reducing unnecessary activation and promoting immune tolerance. In this way, vitamin D supports a balanced immune response — strong enough to protect, but not so aggressive that it turns against the body’s own tissues. Is there evidence that vitamin D promotes effective immune function? Yes, a growing body of research supports the role of vitamin D in promoting effective immune function in a wide range of immune-related outcomes, including: Infections: Some studies have shown an association between low levels of vitamin D and increased susceptibility to colds, flu, and viral illnesses as well as reduced infections with vitamin D supplementation. For example, a randomized controlled trial of vitamin D supplementation by frontline healthcare workers in Mexico found that participants receiving 4000IU/day of vitamin D had a lower rate of infection with SARS-CoV2 compared to those receiving a placebo. Similarly, another randomized controlled trial found that vitamin D supplementation by children aged 2 to 5 years with 2000IU/day reduced infection with influenza (but not enterovirus). Autoimmune diseases: Because of its role in regulating immune function, vitamin D has garnered attention for its potential role in influencing autoimmune diseases. The VITAL study, a large-scale randomized trial, found that participants taking 2,000 IU of vitamin D daily (combined with omega-3 fatty acids) for five years experienced a 22% reduction in the incidence of autoimmune diseases, including rheumatoid arthritis and psoriasis, compared to those receiving a placebo. Similarly, a comprehensive review highlighted that numerous studies have found correlations between low vitamin D levels and both the onset and progression of MS. Additionally, a scoping review focusing on MRI findings in MS patients reported that higher vitamin D levels were associated with fewer new active lesions and reduced lesion volume, suggesting a potential protective effect. Cancer: Emerging research suggests that vitamin D may play a significant role in cancer prevention and management. A comprehensive umbrella review of 71 systematic reviews found that vitamin D₃ supplementation was associated with a 10% reduction in total cancer mortality (odds ratio , 0.9; 95% CI, 0.87-0.92; P < 0.01). Additionally, an analysis indicated that achieving higher serum 25-hydroxyvitamin D concentrations could potentially reduce cancer incidence rates by approximately 70%. These findings underscore the potential of vitamin D in reducing both the occurrence and mortality of various cancers. Inflammatory responses: Vitamin D also appears to help regulate inflammation in the body, acting almost like a natural “dimmer switch” for the immune system. Several studies have found that vitamin D can reduce the production of pro-inflammatory molecules — the kinds that are often elevated in chronic diseases — while increasing anti-inflammatory compounds. This balancing effect may help explain why low vitamin D levels are often linked with higher levels of systemic inflammation. For example, a study found that people with lower vitamin D levels had significantly higher levels of C-reactive protein (CRP), a common marker of inflammation in the blood. While more research is needed, these findings suggest vitamin D may support overall immune balance, not just in response to illness but also in maintaining a healthy baseline state. How much vitamin D is needed for optimal immune function? While it’s clear that vitamin D plays an important role in immune regulation, there is no universally agreed-upon amount that guarantees optimal immune function. Research continues to evolve, and current recommendations vary widely depending on the source. Most guidelines were designed with bone health in mind and may not reflect what’s truly needed for immune support or chronic disease prevention. Blood Levels (25-hydroxyvitamin D) Vitamin D status is measured by a blood test that checks for 25-hydroxyvitamin D , the circulating form of the vitamin. Deficiency is typically defined as anything below 20 ng/mL (50 nmol/L), but for immune function, many researchers argue that this threshold is far too low. Levels of at least 30 ng/mL (75 nmol/L)are often cited as a baseline, but some of the strongest evidence — including large trials like the VITAL study — suggests that 40–60 ng/mL (100–150 nmol/L) may offer the most benefit for immune system balance and resilience. Raising blood levels into this optimal range can be surprisingly difficult with low doses. Many people — especially those with darker skin, higher body weight, or limited sun exposure — require higher intakes for levels of blood vitamin D to increase. Daily Intake (From Diet and Supplements) Although official government recommendations suggest 600–800 IU per day for adults, this level is primarily intended to prevent bone disease, not to support optimal immune function. A growing number of clinicians and researchers now advocate for daily intakes of 2,000–5,000 IU to achieve and maintain optimal blood levels for immune health — especially in people who live in northern latitudes, use sunscreen regularly, or spend most of their time indoors. In fact, research has shown that intakes up to 10,000 IU per day are safe for most people, with no evidence of toxicity at these levels in healthy individuals over extended periods. The commonly cited upper limit of 4,000 IU/day was set conservatively and has been challenged by multiple studies that demonstrate a much higher threshold for risk. Ultimately, because vitamin D needs vary based on genetics, lifestyle, and current levels, the most reliable approach is to test blood levels periodically and tailor supplementation accordingly. Why should vitamin D be taken with vitamin K? Many health professionals recommend pairing vitamin D3 with vitamin K2(typically in the MK-7 form) to ensure that calcium metabolism stays properly balanced — especially when supplementing with higher doses of vitamin D. Vitamin D and vitamin K work together to support not just immune health, but also calcium balance and cardiovascular safety. One of vitamin D’s primary roles is to help the body absorb calcium from the diet. But once calcium is in the bloodstream, vitamin K helps direct it to the right places — such as bones and teeth — and away from soft tissues like arteries, where excess calcium could contribute to plaque buildup. What makes Fringe Vitamin D & K Mix the best in the market? Fringe Vitamin D & K Mix, providing 2,500 IU of vitamin D3 per day, aligns well with the evidence-based perspective of doses that support optimal immune function. It also has three unique characteristics that make it a better choice than other Vitamin DK supplements on the market: Water Solubility – Both vitamin D and K are fat-soluble vitamins, which makes their absorption of fat-soluble vitamins complex and results in a lower bioavailability than water-soluble vitamins (bioavailability refers to how much of the ingested nutrient is delivered to body tissues). The bioavailability of fat-soluble vitamins can be increased significantly through a safe and simple conversion process that makes them water-soluble and able to readily be absorbed through the walls of the small intestine. Research has demonstrated that water-soluble vitamin D is about twice as bioavailable as fat-soluble vitamin D. Vegan D3 – Research has clearly demonstrated that vitamin D3 is superior to vitamin D2 at raising blood levels of 25-hydroxyvitamin D. The vast majority of vitamin D3 supplements source the vitamin from sheep’s wool, which produces a waxy substance called lanolin. Because it is animal based, lanolin-derived vitamin D3 is not suitable for vegans. In contrast, Fringe Vitamin D & K Mix uses the only vegan source of vitamin D3, which is lichen. Lichens are living organisms that consist of fungus combined with algae or cyanobacteria. Lichen-derived vitamin D3 is identical to that produced from sheep’s wool, but is non-animal based, making it suitable for everyone. Vitamin MK-7 - Fringe Essentials Vitamin D & K contains vitamin MK-7, the most bioavailable form of vitamin K. It is derived from the fermentation of Nattō, which is plant-based and suitable for vegan diets. Other ingredients The other ingredients in Fringe Vitamin D & K Mix are all natural and non-GMO. They include inulin and myo-inositol (also sometimes called vitamin B8) to help with dosing, medium chain triglyceride (MCT) oil to help with emulsification, and licorice extract for increased bioavailability. All our products are verified by independent third-party lab testing to ensure that they are free from molds, pesticides, mycotoxins, and heavy metals. We also leave out all the stuff you don’t want like artificial sweeteners, additives, gums, and ‘natural flavors’. Conclusion Vitamin D plays a vital role in helping the immune system function effectively and stay in balance. While there’s still some debate about the exact levels needed for optimal immune function, a growing body of evidence suggests that many people benefit from higher blood levels and daily intakes than current guidelines recommend. Maintaining healthy vitamin D levels is one of the simplest and most impactful steps you can take to support long-term immune resilience, and Fringe Vitamin D & K Mix is an ideal supplement to help you achieve this goal.
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Red Light Therapy for Gut Health
The Human Gut The human gut, also known as the gastrointestinal tract (GI tract), consists of the esophagus, stomach, small intestine, and large intestine. In simple terms, it is a tube or passageway for food that passes from the mouth to the anus. Each part of the gut has its own job to do, which is usually described as the digestion and absorption of food, and the excretion of digestive waste products. In recent years, however, a critical new role has emerged for the human gut, specifically the large intestine. As the last part of the GI tract, the large intestine receives food after most of the nutrients are absorbed and functions to reabsorb water and some remaining minerals. While this final step in the processing of food is essential, equally (if not more) important is the role of the large intestine as host to the gut microbiome, which is being described as a “major determinant of health.” The Gut Microbiome The human body contains over 150 times more genes from resident microorganisms (such as bacteria, viruses, and fungi) than from its own human cells. With a total weight of just over 2kg, microbial cells outnumber human cells by around 10 to 1. Most of these organisms went unrecognized until the last two decades. However, we now know that the body is literally teeming with invisible inhabitants, which comprise what is referred to as the human microbiome. The combined human and microbiome genome is referred to as the “holobiome”. The term “resident” is an apt descriptor when it comes to the microbiome. These organisms live inside the body, from birth to death. They also reside on the surface of the skin. And while the germ theory of disease has conditioned us to believe that most microorganisms are pathological, in fact the human microbiome is one of the most important biological predictors of health. The opposite is also true: alteration in the microbiome is an important predictor of disease. The microbiome communicates with the body, and the body communicates with the microbiome. This crosstalk is essential for human health. The human microbiome can be broken down into several divisions, based on location. The microbiome that lines the mouth is the oral microbiome; the microbiome that lines the skin is the cutaneous microbiome; the microbiome that lines the vagina is the vaginal microbiome; and the microbiome that lines the digestive tract is the gut microbiome. The gut microbiome is the most well researched biome. The role of the gut microbiome is complex and spans a wide range of diverse functions. Gut microbes are involved in the metabolism of carbohydrates, lipids, and proteins, and help to extract nutrients from food. In the gut, they produce useful molecules such as short chain fatty acids and vitamin K. Gut microbes also manufacture neurotransmitters such as serotonin, and through the gut brain axis, regulate many aspects of cognitive function. The microbiome is also involved in the metabolism of ingested drugs and toxins. The gut microbiome starts its development in utero and continues throughout the fetal period, with further colonization during delivery. Most gut microbes are acquired post partem, with breast milk as an important source in early life. A diet containing predominantly plants and whole foods is considered optimal to support the gut microbiome, with fiber being of utmost importance. Processed food, food that is high in sugar, and low fiber diets are bad for gut health. It has been recommended that dietary guidelines be revised to support a healthy gut microbiome. In addition to diet, there are several other factors that influence the health of the gut microbiome. According to the Canadian Digestive Health Association, non-dietary ways to strengthen the microbiome including: avoiding antibiotics, regularly sleeping for at least 8 hours per night, getting regular exercise, and engaging in stress reducing activities. Evidence is also accumulating that gut microbiome health can be supported by therapy with red and near infrared light. Light Therapy Light therapy (also known as photobiomodulation) is the application of light with specific wavelengths to the body for the purposes of influencing biology. The most common form of light therapy uses red light (RL), which is visible as the color red, and/or near infrared light (NIRL), which is not visible but can be felt as heat. The RL used in light therapy usually ranges from 600 to 700 nanometres (nm), with the unit nm referring to distance the light wave travels in one cycle. The NIRL used in light therapy usually ranges from 800 to 900nm. RL and NIRL are naturally produced by the sun, which gives off solar radiation. The term radiation describes energy that is transmitted in the form of waves or particles. The spectrum of light in our environment consists of both light we can see (visible light) and light that our eyes can’t perceive (invisible light). This is called the electromagnetic spectrum. The visible light spectrum is quite narrow, consisting of wavelengths that range from 400 to 700nm and span from violet to red in color. RL is part of this visible light spectrum, while NIRL is not. Red and near infrared light therapy is the application of artificially generated light in the red and near infrared spectral bands. The term “red light therapy” usually describes the use of both RL and NIRL, although only the red light produced by the device is visible to the naked eye. IRL can still be perceived by the body as heat when it contacts skin. How Does Red Light Therapy Affect Gut Health? Red light can affect gut health both through effects on the microbes in the microbiome, as well as on the gut cells of the human host. It’s hard to tease out precisely what is happening in this complex microenvironment, but one thing is clear: light therapy administered to the gut has a positive biological effect. Research has indeed shown that light can modify the microbiome. For example, when RL or NIRL was applied to the abdomen of mice, the composition of the microbiome shifted to include more of a bacterial strain that is associated with better health. Bacteria have also been found to respond to the direct application of RL. Light therapy also impacts human cells. Light is absorbed in cells by molecules called chromophores, many of which are found inside the mitochondria. Mitochondria are the powerhouses of the cell, which make the energy currency of the cell known as ATP. Mitochondria are also involved in regulating the production of molecules called reactive oxygen species (ROS), which play a role in normal cellular function but can be harmful in high amounts. This is known as oxidative stress. Through its effects on mitochondria, light therapy can increase cellular energy production and modulate oxidative stress. Intestinal oxidative stress is associated with disease. Through effects on cellular metabolism and ROS production, as well as through reduction of other molecules such as reactive nitrogen species and prostaglandins, light therapy can decrease inflammation. Both RL and NIRL have anti-inflammatory effects, and unlike anti-inflammatory medications (such as NSAID’s), do not cause side effects. Inflammation is a hallmark of many gut disorders, such as Crohn’s Disease and Ulcerative Colitis. By improving the health of the gut (both the microbiome and human gut cells), a wide range of positive effects are observed, including: Improving communication between microbiome and the rest of the body. Improving digestion of food and production of energy and nutrients. Decreasing inflammation and production of reactive oxygen species. Increasing production of short chain fatty acids involved in immune function. Improving the health of the gut lining. Gut Dysbiosis When the gut microbiome is dysregulated, there is an adverse effect on its human host. This is called gut dysbiosis. Poor dietary choices, sedentary lifestyle, increased stress, and use of antibiotics (and other pharmaceuticals) can cause the gut microbiome to become unhealthy. This causes a loss of integrity of the gut lining, also known as leaky gut. In turn, the gut becomes permeable to things like microbes and food fragments, which activate the immune system and trigger an inflammatory response. Chronic inflammation ensues, and a vicious cycle is established in which the gut becomes increasingly compromised, which worsens the inflammation. Dysbiosis also impairs metabolism. Gut dysbiosis has been associated with an enormous range of human disease, including metabolic syndrome, neurological disorders, immune system disorders, autism, psychiatric disorders, obesity, systemic inflammation/autoimmunity, type 2 diabetes, chronic pain, multiple sclerosis, inflammatory bowel disease, and eye diseases. A 2021 article in The Guardian described that “The great opportunity – but also the great difficulty – of gut microbiome science is that poor gut health is associated with such a vast range of conditions.” This means that there is enormous potential to reduce human disease by improving the health of the gut microbiome, although it is important to acknowledge that our understanding of these relationships is still limited. Clinical Applications of Light Therapy to the Gut The use of light to improve health dates back thousands of years. Sunlight has been used in medicine since at least the time of the Ancient Greeks, to treat conditions such as tuberculosis, skin disorders, and bacterial and fungal infections. However, the practice fell out of favor during the 20th century as modern societies embraced the medical pharmaceutical model of therapeutics. Over the last decade, there has been an increasing interest in harnessing the power of light as a therapeutic, and a wide range of applications are being explored. Several studies have investigated what happens when RL and/or NIRL light is applied to the abdomen. Interestingly, the bulk of this research has been done using abdominally applied light to treat brain disorders, rather than for GI tract diseases. This is because of the important relationship between the gut microbiome and the brain, through a pathway known as the gut-brain axis (GBA), which involves bidirectional communication between the gut (including the microbiome) and the brain. The GBA plays an important role in brain, gut, and immune health. Alterations in the gut microbiome may be associated with disease through the GBA. RL and NIRL applied to the abdomen (as well as the neck, head and nose) of Parkinson’s disease (PD) patients has been shown to modulate the composition of the gut microbiome, with a shift towards more “healthy” bacteria. Light applied to the abdomen and neck for 12 weeks also decreased symptoms such as impaired mobility in PD patients, with improvements lasting for up to a year. PD is a degenerative brain disease that causes motor symptoms (such as balance and gait problems) and non-motor symptoms (such as depression, sleep disorders, and cognitive impairment). It affects around one million people in the US, and over 10 million people globally. Application of RL and NIRL to the abdomen (as well as the head) has also been used in the treatment of Alzheimer’s Disease (AD). In a 2022 clinical trial of patients with mild to moderate AD, those receiving light therapy showed improved cognitive function relative to the control group. Alzheimer’s Disease (AD), a form of dementia, is a neurodegenerative disease that comprises 70% of dementia cases. AD affects 1 in 10 US adults over the age of 65, or 5.7 million Americans. It has been suggested that light therapy applied to the abdomen may be useful in reducing depression. The composition of the gut microbiome has been linked to depression, with depressive patients showing higher levels of certain bacteria that are involved in the synthesis of neurotransmitters such as serotonin and GABA. These neurotransmitters are involved in the regulation of mood. Gut microbiome composition has been strongly associated with mental well-being. Given the associations between brain diseases and the GBA, it has been suggested that targeting the microbiome holds great potential in the treatment of neurodevelopmental and neurodevelopmental diseases. In addition to AD and PD, these include diseases such as multiple sclerosis, autism spectrum disorder, attention-deficit hyperactivity disorder, migraine, post-operative cognitive dysfunction, and long COVID. According to researchers from Australia, many studies are currently underway “with the aim of restoring the microbiome and potentially altering the course of these brain conditions.” Light therapy may also be helpful in modifying the microbiome in diseases that primarily affect other body systems. For example, in a case report of a patient with breast cancer, application of NIRL to the abdomen was associated with increased diversity of gut microbes, which is considered to be a healthy change. The authors suggest that light therapy may be a way to improve gut health in patients with chronic disease. Most patients with chronic disease use medications which may adversely affect gut health (especially the microbiome). There is also great potential to use light therapy to treat gut disorders. For example, animal research has found that application of RL to the abdomen of rats with experimentally induced colitis (a form of inflammatory bowel disease) improved many markers of gut health, including reducing inflammation. There is interest in studying the use of light therapy to improve gut health in human subjects as well. Notably, a study using NIRL applied to the abdomen (as well as the front of both thighs) is currently underway to assess whether treatment reduces pain, fatigue, and depression in patients with inflammatory bowel disease. Effects on the gut microbiome will also be measured. Using Light Therapy for Gut Health There are many light therapy devices on the market today that could be used at home to target gut health. With so many options available, how can you know which device is best for you? Here are five issues to consider. Style Preference: To treat the gut with light therapy, light should be applied to the abdominal area. Two types of devices are most appropriate for abdominal applications: (i) a light panel, or (ii) a light wrap. Your personal level of comfort with a device is important. Imagine yourself using it – Do you want to stand in front of the device, or would you prefer the flexibility of being able to lie down while wearing it? Do you want a device that is wireless, or can you commit to being close to an electrical outlet so that you can plug it in? Think about your personal preferences and choose accordingly. Laser vs LED: Light therapy is administered using either laser or LED lights. While early light therapy research was done using lasers, LED lights have become much more popular over the last decade. The research described in this article includes both types of light sources. In 2018, Dr. Michael Hamblin – the world’s leading light therapy expert – concluded that LED lights using comparable parameters to lasers performed “equally well”, which is very important because LED powered light therapy devices can be made at a fraction of the cost of laser devices. For at home use, look for a device that uses LED lights as safe and affordable option. Light Color/Wavelength – As described in this article, both RL and NIRL have been used in studies of light therapy to treat gut disorders. Positive results have been observed when these wavelengths were used either together or individually. So, look for products that use RL and NIRL either alone or in combination. Light Intensity – Light intensity refers to the amount of light being delivered by a device. It is also referred to as irradiance. The required intensity when using light therapy to impact gut disorders is unclear. There is variability in light intensity between studies, and no studies have directly compared different intensities. Since light is being delivered to the skin of the abdomen, it may be prudent to follow the advice given for light therapy to the skin, and mimic the intensity of the sun, which is around 24 mW/cm2. This is described as the “sweet spot” between higher intensities, which can have harmful effects, and lower intensities, which will have no effect at all. Placing a high intensity device directly on the skin could be harmful. Choose a sun-mimicking product and don’t overdo it when it comes to treatment frequency and duration. Education – While light therapy education will not change the specific functionality of a device, it does have the potential to profoundly impact how someone uses the technology. When a company provides evidence-based education that teaches consumers why, how, and when to use a product, devices can be used to better support healing. Look for products with accompanying education and instructions for use, whether in printed and/or digital formats. You can also look for companies that provide support by phone or email to current or prospective customers. Conclusion Hippocrates is credited with stating that “All disease begins in the gut”. While today’s science does not yet support that level of conviction, we do know that gut health is intimately associated with the overall health of the human body. We also know that “what happens in the gut doesn’t stay in the gut”, but rather influences other organs and systems through complex communication networks. The gut microbiome is inextricable from our own human gut, and both are important for optimal health. When using light therapy for gut health, it’s important to also engage in other gut-friendly activities. These include eating a gut healthy diet, staying hydrated, exercising regularly, and limiting stress. It’s advisable to work with a health care provider with expertise in this area and who can provide appropriate support. Many questions remain about how light therapy can be used to support gut health, but preliminary pre-clinical and clinical evidence supports the use of RL and NIRL both to induce healthy shifts in the gut microbiome and to decrease inflammation. Since RL and NIRL also have other effects, such as increasing energy and decreasing ROS production, many other benefits are likely to be observed. This is certain to be an area of active research interest, especially given the amazing safety profile of light therapy and the increasing availability of at-home devices. For more information about Fringe light products, go to: https://fringeheals.com/shop-all-products/
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